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Night owls have more mental stamina than those who awaken at the crack of dawn (theglobeandmail.com)
81 points by soundsop 2182 days ago | 41 comments



Here we go again...

People with nothing but their own anecdotal experience about the subject trying to (and failing at) criticizing a scientific paper. No one has pulled off a "correlation != causation", but most other usual suspects are already there.

Disclaimer: 1) I work in neuroscience , but not in sleep research. This (hopefully) makes me qualified to assess the seriousness of the methods, even though I don't have much background in circadian rhythms. 2) I'm biased in this case since I know personally the first author of the paper and some of the other researchers involved (and they are among the smartest and more conscientious people that I know of).

If there were any methodology error lay people would be able to spot in the paper, it wouldn't have been published in any respected journal in the field (and most people who commented here are lay people regarding (sleep) science). This is Science Magazine... They have the best reviewers in the world ("best" as in "smarter than you can probably imagine").

There are shortcomings inherent to this kind of study, of course. You cannot control experimental parameters like you can in physics or chemistry. That's why you have to 1) build your research on solid ground (i.e. solid results already published and reproduced) and 2) be as careful as possible in designing your protocol in order to have your bases covered. Schmidt et al. used the gold standard, they're frankly out of reach of such "low hanging" criticism.

</rant>

I enjoin you to have a look at the paper and the supporting material.

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Full text: http://www.innovatieforganiseren.nl/wp-content/uploads/2009/...

Supporting Online Material: http://www.sciencemag.org/cgi/data/324/5926/516/DC1/1

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Here's the beginning of the latter:

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1. Material and methods

Subjects.

[Ethical committee disclaimer]. [All subjects] were screened for morningness or eveningness according to their timing preferences as defined by two questionnaires (MEQ (1) and MCTQ (2)). The two groups were matched according to age, sex and educational level and did not differ in their anxiety and depression levels as well as in sleep quality and day time sleepiness (all ps > 0.1; Table S1). Morning and evening types significantly differed in their scores on the two chronotype questionnaires (MEQ and MCTQ). Exclusion criteria were reports of medical, psychiatric and sleep disorders, medication or drug consumption, alcohol abuse, excessive caffeine consumption or physical activity, shift work within the three past months, and transmeridian travel or disturbances in the sleep-wake cycle within one month before the experiment.

Design and Procedures.

An overview of the study design is illustrated in Fig. 1 of the main text. Individual times were scheduled according to each volunteer’s preferred sleep and wake timing. Criteria for such timing preferences included sleep schedules adopted on free days as assessed by the MCTQ (2) and after interviewing the subject to ensure that the scheduled timing was as close as possible to the schedule that he or she would spontaneously adopt. In a second step, the screened subjects came to the sleep facility for a habituation night. After this night, they were asked to follow the sleep schedule (± 30 minutes) they would spontaneously adopt while free from any social and professional constraints. Target bedtimes and wake times were determined for a sleep duration of about 8 h (± 30 minutes). To assess the subjects’ compliance to the selected rest-activity patterns, motor activity of the non-dominant arm was recorded using actimeters the week prior to the experimental sessions along with sleep-wake logs. After this week under actimetry recording, subjects came to the sleep laboratory for 2 consecutive nights. The precise schedule of each session was individually adapted according to the subject’s habitual bedtime on the basis of the mean timing of the subject’s sleep midpoint derived from actimetric data of the preceding week.

Subjects reported to the laboratory 7 hours before habitual lights off on day 1. After the hook-up of the electrodes, they continuously stayed under controlled conditions in dim light (< 10 lux) in order to avoid the influence of bright light on circadian rhythmicity parameters (3) and in the aim to equalize pre-scan conditions between subjects. Subjective sleepiness (Visual Analogue Scale (VAS) and Karolinska Sleepiness Scale (KSS (4))) and objective vigilance (a modified version of the PVT (5)) were assessed at hourly intervals while awake. Furthermore, hourly collected saliva samples were assayed for melatonin using a direct double-antibody radioimmunoassay validated by gas chromatography-mass spectroscopy with an analytical at least detectable dose of 0.65 pg/ml (6). Circadian phase was estimated by the calculation of the mid-range crossing time of salivary melatonin (7, 8). For each individual curve, the maximum value and the minimum value was averaged (mid-range value pg/ml) and taken to determine the mid-range crossing time (time of day, h) on the abscissa.

Polygraphic data (see below) were recorded during the nights preceding fMRI sessions. After lights off, subjects were allowed to sleep for 8 hours. Then, 1.5 (morning session) and 10.5 (evening session) hours after wake up of scheduled sleep timing, they underwent a fMRI session during the practice of various cognitive tests, including the psychomotor vigilance task on which we focus here. For half of the subjects, the morning session followed the first experimental night and the evening session the second night, whereas for the other half of the volunteers the morning session followed the second experimental night and the evening session the first night. Subjects were allowed to leave the facility between the two experimental nights. They stayed in the laboratory under dim light conditions (<10 lux) for at least 4 hours before the scanning sessions (see dashed line in Fig. 1). They wore protective glasses avoiding excessive light input when going to the scanner room.

The order of selected cognitive tasks was counterbalanced across subjects and sessions. Before the start of the experimental protocol, all subjects underwent a short habituation scan session in order to familiarize them with the noise and the body positions associated with the fMRI environment.

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It's an inflammatory article. The opening sentence is blatantly antagonizing. It makes a broad generalization about what "mental stamina" means and presumes it is an unqualified Good Thing. There are days when I accomplish more mental work between the hours of 7 and 9 than the entire rest of the day. Sure, late in the day I run out of steam, but I don't really care.

The actual results of the test are not nearly so offensive to the "smug early birds" as you might think. The study controls for caffeine and physical activity, among many other things. There's a gap between what the study actually was testing, and the everyday semantics of the terms "early bird" and "night owl" which is glossed over by the article.

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"In their relative evening, late risers are more alert and can outperform early birds in a reaction time test assuming they're allowed follow their natural sleep rhythm, whereas there are no such differences in the morning" would be a more accurate title...

The paper also gives insights relative to the neural processes involved.

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There's that term again. How do we know that real life "early birds" and "late risers" are actually following their natural sleep rhythms?

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Some do, some don't. Most people go back to their natural patterns during the holidays, though. The classification is based on forms asking questions in a context of freedom from external constraints.

I'm not very familiar with sleep research, but I'd guess that both types will underperform if their natural penchant is disturbed (by work hours, for example).

Edit: Here is the actual screening form (in French) used for the studies: http://www2.ulg.ac.be/crc/in/CIRCADIEN_ONLYweb.html ... Adapted from: Horne, J. A. and O. Ostberg (1976). "A self-assessment questionnaire to determine morningness-eveningness in human circadian rhythms." Int J Chronobiol 4(2): 97-110.

Extreme early and late subject are further "diagnosed" with more exhaustive tests.

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Interesting, thanks.

I do want to make it clear I wasn't trying to attack the study so much as explain why people get upset and respond to something like this with anecdotal comments.

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It was clear, to me at least :-).

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I'm not sure where your perceived disconnect between mental stamina and running out of steam is. (Additionally, could you say how mental stamina is a bad thing, ceteris paribus?)

Could you elaborate on your definitions for "early bird" and "night owl"? My everyday semantics align with the article.

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My comment was mainly to point out the lack of context, and could have been clearer. But mental stamina may not be a good thing emotionally, that isn't really explored. The term mental stamina is fine, since that's what the study was about, but the first paragraph over-emphasizes the value judgment in order to antagonize and stimulate argument. So with an article like that, don't expect the responses to be intellectual.

Could you elaborate on your definitions for "early bird" and "night owl"? My everyday semantics align with the article.

An early bird, to me, is someone who likes getting up early and usually does. An early bird, according to the study, is someone whose natural circadian rhythm is shifted earlier in the day. A night owl, to me, is someone who regularly stays up late. According to the study, it's someone whose natural circadian rhythm is shifted later in the day.

In everyday use, night owls include people who stay up late and sleep late because they like getting hammered. In everyday use, early birds include people who force themselves out of bed at the crack of dawn with an alarm clock and a cup of coffee. In every day use, the terms apply to people who may spend significant portions of their day engaged in physical activity. None of those people fit the definitions used by the study (as I understand it, anyway)

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a lot of the information you just shared is not in the article that was linked.

if had been then I would not have called it to be superficial. I mistakenly assumed with the tone of the article, that it would make as strong of a point that it could, and this article, presented very little information about all these additional constraints and steps you mentioned.

Now knowing about all these additional steps, I'm still left pondering - what if high energy people shifted their sleep patterns? I'm a night owl, and I'm generally a high energy kind of person, but if I was to shift my sleep so that I went to bed earlier and woke up earlier (although tough to pull off for me), maybe my energy would go with me, shifting to earlier in the day.

I think that would make a good follow up study: take those night owls and perhaps the early rises as well, and shift their sleep up and then do all these measurements again to see how it affected them. Did they drop in energy, or did their energy go with them through the transition (giving them time to adjust as well).

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They give the name of the main authors (first and last), and the journal in which it has been published in the same paragraph, which is actually amazing in a vulgarization article...

Usually, you can be happy if they named one of the investigators. It's all about "scientists".

That said, it's true that the article itself is light on facts. The fact that the paper had been published in Science was a good hint, though.

I don't think that your "high energy" profile is related to your late profile.

Disrupting the natural sleep tendencies (usually) results in diminished energy. The early vs late type depends on a balance between the day/night light variations, and an internal clock that produces an internal sleep pressure.

I think that early people have an endogenous cycle shorter than 24 hours, and the opposite for the late type.

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Here we go again...

People whose only involvement is friendship with the author defending said author from comment from the peanut gallery and using arguments such as "you probably don't know anything about this subject", "stop thinking and just trust the publication", "don't criticise the reviewers, they're smarter than you. Smarter than you can even imagine. How dare you think you have anything worth saying?".

And of course, the brilliant: "You're failing therefore I'm looking down on you, why not stop now?"

This is HN, not a peer reviewed science journal. Comment here is no real threat anyway, and even if it was a real threat, if the paper is as solid as you say then it wouldn't be affected anyway. Get down from your high horse and let discussion happen. Some of us might even make mistakes and clarify our understanding of some part in the process. (How dare we!)

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I'm sorry I killed the discussion... and you have a point regarding my patronizing tone. I should have refrained from replying to specific comments, but it got on my nerves. Most of these are bordering the "not even wrong" kind.

The usual behavior towards this kind of ignorance and arrogance is contempt. I could have kept shut and let people make fools of themselves but, somehow, I care about this place and the quality of the community, hence my reply.

I probably wouldn't have been as vehement hadn't I known (remotely for most of them) some of the authors, hence the disclosure, but that's not the point.

The criticism below come from people who, by the fact of their comments, displayed flagrant ignorance of the subject and of the scientific process, and imagined they could criticize the paper on a technical ground when they are clearly incompetent to do so. Hence the link to the original paper and the information complement ==> "Please read the paper and make your opinion based on it rather than on a simplified summary".

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I know of course that there are smart people outside the academic world. That's why I'm hanging around here. But the Science reviewers are the best researchers in their fields, and, to get there, you need to be impressively smart and knowledgeable. I hope you've had or will have the chance to hang around with people in that "league", they are amazing. Assuming you can outsmart them at reviewing a paper without having even read it is just dumb.

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At last, I didn't see the comments here as threats to the paper it is solid, and so are the people behind it. I wouldn't have written the comment if I had a single doubt about it. The Cyclotron team routinely publishes papers in the best journals (Science, Nature, PLOS, PNAS, the Lancet, to name a few). They're badasses ;-)

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You didn't kill the discussion. Everyone is entitled to an opinion, but not everyone's is necessarily informed. Pointing out that people who only have a casual, indirect understanding of the material at hand should keep this in mind when attempting to critique the paper is a perfectly valid, non-elitist, thing to point out. Quite frankly, even if I were to read the paper, I probably would not have enough understanding to make an informed opinion on the subject. I can give a bunch of javadoc class descriptions to a neurosurgeon. But that doesn't mean that she'll have the prerequisite knowledge to make sense of it.

We should celebrate our specialties and the amount of narrow and deep knowledge required to become experts in them instead of having our egos tripped up because we can't have our intelligence validated in every single domain.

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I know a future neurosurgeon who, as a teen, used to code 3D demos in 80386 assembly... Including whipping on his own linear algebra routines, for the fun of it...

That said, I agree with your point, and thank you for your support.

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get down from your high horse and let discussion happen

That's exactly what he did, and he did it so well, the stupid parts of the discussion can now end, and that's a good thing.

Also, Mr. Pot you might not want to go out of your way to point out black kettles.

I guess what I'm saying is YOU get down from your high horse let discussion happen.

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I've done both - spent time working early mornings and also into the night. I found that working early in the morning I'm more productive per hour than I am at night. I find nighttime working to be more creative though. The mornings are good for me "getting things done" and by 9-10am all the planned work I had was done

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My experience mirrors this. I get through a lot more work and admin in a given day if I work from 7am-4pm, especially if there's a lot of drudgery involved. In contrast, if I work from 9am-6pm or later I'm more likely to procrastinate but I get a spurt of creativity that starts in the late afternoon and gets amplified at night. So I try to structure my work day around that, using early mornings to race through necessary but boring work and to tie up the remaining loose ends from the day or night before while leaving particularly challenging problems for later in the day or the evening. Not to mention that the feeling of getting a bunch of tasks out of your way early in the morning usually acts as a potent motivator for the rest of the day.

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I'm the same way (and I used to hate morning).

I'm not sure if it's a product of it being quieter in the early morning when I first wake up (as opposed to at noon), the fact that recently I've been alone in the "office" for most of the day, or what, but I definitely find it easier to get into "the zone" in the morning and get a lot of work done.

I'm writing code 8-12 hours a day now, which is pretty outstanding considering it isn't a new project or something. The fact that I'm exhausted by about 8pm doesn't really bother me.

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I'm not a morning person, but my experience is similar to yours. What I settled on when circumstances allow for it is to wake up early in the morning to get non-creative stuff done. Then, I have a nap for maybe 2 hours. Following this nap, I continue on with my day, first taking care of the new work generated by my first round of morning work, before settling in on the meat of what I do when most people are winding up for the day.

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although this may be true, the study is quite superficial. personally, my issue with sleep has been that if you leave me alone in a dark room (like in my bed), i'll come up with all sorts of ideas... also, distractions taper off as the night progresses, and i'll be like 'k, this feature, then done' - but then you realize you need another feature but you have all this information in your head you need to get out -- and the details keep piling in. if you were to jot down notes, you might as well have coded it and tried it out.... and then you realize something else you can do. other nights, you go ah, this is nice, and just know what the next step is and as long as it's somewhat concrete, it's easy to sleep knowing you'll do it tomorrow.

generally, i find it easier to sleep if i've hit one of these plateaus, or if i'm stuck, or if there's too many options of where to go from here; the answer will be clearer tomorrow. It's when the answer is -almost- clear, just need to try out a few things, that sleeping feels like trying to swim upstream.

i've tried to 'fix' my sleep so many times in life now, by which i mean be consistent - and so far, no success. nothing too bad has happened to me, either -- if i don't get enough sleep i know i'm sub-par but i feel capable of at least being 'average' until i get home and get more sleep the next night. on the other hand, i've taken vacation simply because i know if i don't solve this ranking algorithm, i'm going to go insane - so i took three days off (wed-fri, so i got weekend too), and worked through the day and night, sleeping as fit until it was all good, and that itch in my head was resolved.

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I keep wondering what makes researchers doing that kind of work so confident that they have captured all the relevant variables.

It may well be that being a night owl is not just genetic but acquired by people who are unusually motivated to stay alert for longer times. Don't we all know the feeling of not wanting to stop?

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Well, in my experience, the average behavioral researcher isn't so much "confident they have captured all the relevant variables"... as "confident they have a research paradigm that will yield publishable data." —from a recovering academic

As for "Don't we all know the feeling of not wanting to stop?"... maybe us on HN.

But your comment raises a significant issue: those who do readily get into that "not wanting to stop" place are likely to end up working late because of that engagement (and hence focus).

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That feeling of not wanting to stop, while responsible for most of my noteworthy accomplishments, scares a lot of people. I have had several people who have tried to "fix" me because they decided that me being up most of hte night finishing something was unhealthy. They never seem to understand the idea of ramp up time, nor do they seem to understand the fickle mistress inspiration. There was one guy, a kind of mentor to me, who tried to tell me it was a moral imperitive to get up early and get to work, to show the bosses I cared. For some reason staying late didn't show the same thing, particularly if i took advantage of the flex time and showed up around noon. Fortunately this guy was not my boss, and instead I get to be productive in the way that fits me best. Fortunately this guy broke off the mentorship after I got promoted in spite of my "terrible scheduling habits".

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It's easier to observe and control for the sleep schedule and then measure alertness, rather than the other way around.

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working my regular job and doing a side startup has def made me embrace the night-owl shift. I find that my first hour of night work, say 9-10, is less productive then I'm able to pick up the pace from 10-1, at that point I have to go to sleep or I'm wrecked the next day. Ideally, when I'm able to go 100% on the startup, I would work from 8:30-5:30, come home chill with the fam, then work 9ish-1ish. that way I get 6 hours sleep, have time to hang with kids and still put in a solid 12-13 hours. funny that my dream is to be able to work 13 hours a day, but its really about doing something I love and own, and the crazy hours are a side result.

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If you have a startup and a day job I urge you to secretly work on your startup as much as you can while at your day job. This is wrong, but gotta do what you have to do to do what you want to do.

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"After 10 hours of being awake, the early birds showed reduced activity in brain areas linked to attention span, compared with the night owls."

Yah fine... but this study says nothing about the quality or intensity of the early birds vs. night owls.

10 hours is a pretty long period of time to stay focused. Instead they should compare the mental efficiency of the two groups over a two hour period of focused work.

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> but this study says nothing about the quality or intensity of the early birds vs. night owls.

Yes it does. Sleep length was fixed at 8 hours, and they acquired polysomnographic recordings of both nights spent at the lab and scored the sleep quality. ==> No statistical difference.

They controlled most controllable parameters. Read the paper and the supporting materials.

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> "Yah fine... but this study says nothing about the quality or intensity of the early birds vs. night owls."

No offense, but that sounds like rationalizing the result to maintain your own current prejudices as opposed to a genuine criticism of the research.

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Intensity and focus matter more than stamina.

The stamina that matters is over the course of months or years.

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Why does this cheeky crap article have 52 freaking points? Oh sorry I'm supposed to flag and shut up, not complain.

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The research is interesting, despite the crappiness of the article.

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The claims in the article, including those specifically attributed to the researchers, go far beyond anything justifiable by the research. The "genetics" claim is especially unjustified.

Personally, I can and have slept and worked ANY schedule, as long as I can get enough sleep. Creative work or intense studying though work best with a split schedule, where I have two 3-5 hour sleeping shifts, so I am always fairly fresh.

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The genetic origin of the variation in circadian phenotypes are well documented, and have been for a long time.

You can work against your predispositions, but if you remove social constraints, your natural pattern will quickly re-emerge.

Furthermore, your subjective assessment of your productivity along the day is not really meaningful in this context.

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Smug early birds take note: Night owls actually have more mental stamina than those who awaken at the crack of dawn, according to new research.

"It's the late risers who have the advantage, and can outperform the early birds," said Philippe Peigneux

He's not actually talking about "performance" in a general, life-applicable sort of way; rather he is talking about performance at specific mental tasks. You wouldn't think that from the way the article is written, however.

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Aren't we just comparing apples and oranges here? Is it really that counterintuitive that people who get up at 5 AM tend to not be terribly mentally acute at 3 PM? Is it counterintuitive that night owls would be more mentally acute later in the day?

Let's see a study that measures the mental acuity of extreme morning people at 7AM and the mental acuity of extreme late risers at 2 PM. Better yet, let's measure mental acuity of the two groups immediately upon waking. Surely that must be just as significant as the study above.

Studying the mental performance of two groups when one group is seriously disadvantaged (and if you think people who get up at 5 AM aren't disadvantaged at 3 PM, I think you're not being honest) isn't particularly note-worthy if you ask me.

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The measurements were performed at time points relative to the natural rhythms of the subjects i.e. respectively 1h30 and 10h30 after waking up according to their natural rhythms. Have a look the methods and protocol linked above.

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That's not what the article says. The article seems to draw its conclusions entirely on this statement: "After 10 hours of being awake, the early birds showed reduced activity in brain areas linked to attention span, compared with the night owls."

I saw from your comments above that measurements were taken at two different times. However, the article, not the study, is linked prominently on the front page of HN and that's what I'm taking exception with. I have no doubt that the study is rigorous and careful but the conclusions drawn and the tone taken by the author of the article are sketchy at best.

On top of that, as you mention in a previous comment, the study is comparing what the two groups can do in "their relative evenings". Again, this seems like apples to oranges to me. Of course morning people are going to be less effective in their evenings because, well, they are MORNING people.

I guess I would be interested in understanding what we hope to get from a study like this. The article says people who are extreme in either direction are genetically predisposed to their own personal direction. If we identify that one group of people is better than the other based on their genetics, what does this do for us, long term? That's something I'd be interested in hearing about.

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"After 10 hours of being awake" is correct actually.

For the behavioral part of the study, "In their relative evening, late risers are more alert and can outperform early birds in a reaction time test assuming they're allowed follow their natural sleep rhythm, whereas there are no such differences in the morning" would be more accurate.

For the imaging one: "Ten hours after waking up early birds show patterns of activation similar to those of sleep deprived people (1 night skipped). Late owls show patterns associated with optimal concentration". The sleep pressure in EB is also greater as demonstrated by the amount on slow wave sleep in the first part of the night.

> Of course morning people are going to be less effective in their evenings because, well, they are MORNING people.

Not necessarily. In absolute time, it's obvious it will be the case, but why, beforehand, would it be when you adjust the measurements to the sleep cycle? At least it's not obvious for me. Read the detailed methods in my post above. Furthermore, evening people are as performant as early people in their relative morning. The only difference is in the relative evening where late types are better.

I'm not sure it has much impact in terms of eugenics. The paper shows that late people, who tend to be seen as slackers in general, actually perform better (at some tasks) if they are free to follow their natural rhythm (up at 10+am, go to sleep at 2+ am), which is impossible to do for most of them in the current socio-proffesionnal environment.

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The only reasons I can come up with for pulling an all nighter is that a deadline is near and that it is much more quiet at night. "Increased Mental Stamina" is a metric I'm not familiar with, is that how many pushups your brain can do ?

Mind you, I'm one of those 'night owls', but this quote from TFA is very funny:

"Maintaining their natural schedules, the volunteers spent two consecutive nights in sleep labs. After 10 hours of being awake, the early birds showed reduced activity in brain areas linked to attention span, compared with the night owls. The early risers also felt sleepier and tended to perform tasks more slowly, compared with the night owls, when their level of alertness was measured."

So, the night owls get to maintain their natural rhythms and spend their nights in a sleep lab and so did the early risers ?

But for the night owls that makes the situation totally different than for the early risers, after all, the early risers are going to be quite tired by that time and they'd like to sleep, but being in a different environment they can't or will not sleep as good as they normally would. The nightowls just hang out, go home and sleep it off...

Or am I missing something here ?

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